In electrosurgery, high-frequency electrical energy is generated by an electrosurgical generator and conducted to an active electrode. A surgeon manipulates the active electrode over the tissue of the patient. Depending upon the characteristics of the electrical energy entering the tissue from the active electrode, cutting, cutting with hemostasis and coagulation surgical effects can be created. The electrical current flows from the surgical site through the patient's body to a patient plate or electrode, also known as a grounding pad. The patient plate is of relatively large dimensions to conduct current from a relatively large area of the patient's body. Due to the relatively large conductive surface and the relatively low current density, the energy concentration at the patient plate is insufficient to create tissue burning or other destructive effects at the patient plate.
Establishing and maintaining a proper electrical connection of the patient plate in the electrosurgical circuit is very important to the safety of the patient. Should the electrical connection between the patient and the patient plate, or between the patient plate and the electrosurgical generator become disrupted or discontinuous, earth ground current leakage paths from the patient to the surrounding equipment such as the surgical table can occur. The leakage paths are random and usually involve relatiVely low cross-sectional, high density currents. Burns to the patient can occur as a result of these leakage paths.
Because of the possibility for unintentional patient burns, patient plate continuity sensing circuits have been incorporate in many electrosurgical generators. The patient plate sensing circuits electrically sense the electrical connection of the patient plate to the return conductor of the electrosurgical generator. Should a break in continuity be sensed, the electrosurgical generator immediately terminates its electrical output. The most typical patient plate continuity sensing arrangement involves connecting two return cable conductors at separate locations to the patient plate, and sensing the continuity through the patient plate between the two conductors. This sensing arrangement determines if the patent plate is properly connected to the return conductor of the generator.
Disposable patient plates are typically used in electrosurgery. An electrical connector is therefore employed on the end of the generator return conductor in order to selectively connect to and disconnect from the disposable patient plates. The electrical connector accepts a conductive tongue formed on the disposable patient plate. The tongue of the patient plate is inserted into the connector, and the connector is manually manipulated to retain the tongue during the electrosurgery. The connector establishes the electrical connection through which the continuity sensing current flows and the current path for the high frequency electrosurgical current.
The connector should also create sufficient retention force on the tongue of the patient plate to restrain it against accidental disconnection. Accidental disconnection might occur as a result of someone tripping over the return conductor during the surgical procedure, for example. The patient plate is usually so sufficiently restrained against the patient by a conductive adhesive gel, that a large force on the return conductor might separate the connector from the patient plate. Upon disconnection and before the continuity sensing safety circuit can terminate the output current from the generator, momentary leakage paths to earth ground can cause patient burns. Of course if the generator does not include a continuity sensing safety circuit, the earth ground leakage paths can result in substantial burns and tissue destruction.
To resist accidental disconnection, one prior approach used in disposable patient plates has been to form holes or other special retaining configurations in the tongue of the patient plate. Such special retaining configurations are not universally employed in all types of electrosurgical equipment. Consequentially special patient plates must be used with particular equipment. Generally speaking, more universally usable equipment is generally preferred because it is available from multiple different sources. Accordingly, special retaining devices on patient plates and the corresponding retaining arrangements used in connector clamps are generally not favored.
The patient plate connector should also be relatively convenient for use. An attendant should be able to easily connect the connector to the tongue of the patient plate by holding the connector in one hand and the patient plate in the other hand. The attendant should be able to physically sense the proper operation of the connector in establishing an electrical and mechanical connection to the patient plate. The electrically conductive elements of the connector should be substantially insulated from the outside environment to avoid spaces and openings through which the relatively high voltage electrical energy can be conducted to the external environment. Since the patient plate and the attached connector are sometimes placed fully under the patient laying prone on a table, the connector should be of a configuration which does not physically injure the patient or of a configuration which provides an opportunity for high density current to travel from the patient into the connector by avoiding the larger surface area of the patient plate.
It is with respect to these considerations and others, that the improvements of the present invention have evolved.